1. Field of the Invention
The present invention relates to an electromechanical transducer such as a capacitance type electromechanical transducer which is used as an ultrasonic transducer or the like, and to a photoacoustic apparatus.
2. Description of the Related Art
Conventionally, a micro-mechanical member to be manufactured with a micro-machining technology can be processed in a micro-metric order, and various micro-functional elements are realized by using these members. A capacitance type electromechanical transducer such as CMUT (Capacitive Micromachined Ultrasonic Transducer) using such a technology has been studied as an alternative of a piezoelectric element. Such a capacitance type electromechanical transducer can transmit and receive an acoustic wave such as an ultrasonic wave by using the vibration of a vibration film, and it can easily obtain superior broad band characteristics particularly in a liquid. On the other hand, an ultrasonic transducer has been proposed, which illuminates an object to be measured with an illumination light (near-infrared rays or the like) and receives a photoacoustic wave thereby emitted from an inside of a subject (see Japanese Patent Application Laid-Open No. 2010-075681). The mentioned transducer is provided with a light reflection member for reflecting a light, and this light reflection member is structured so as to be larger than receiving faces of the ultrasonic transducer which receive the photoacoustic wave.